The present invention relates to an image reading apparatus such as a hand-held scanner.
An image or document reading apparatus such as a handy scanner using a compact optical system including, for example, a CCD (Charge Coupled Device) image sensor requires an extended optical path between an original document surface and the CCD image sensor for focusing the image on a small CCD image sensor by means of lenses. Accordingly, an extended long optical path is formed by enabling the optical system housed in a small casing to reflect light a number of times.
An exemplary structure as shown in FIG. 3 is known. The image reading apparatus comprises a casing 1, a lamp 2 for illuminating an original document surface W having images recorded thereon with light, a lens 3 for converging reflected light L which has been reflected on the original document surface W, a plurality of mirrors 4 (medium obtained by vacuum-depositing aluminum on a glass) for guiding the reflected light which has been reflected on the original document surface W while bending it, mirror mounting parts 5 (6) for mounting the mirror 4 on the casing 1, and a CCD image sensor 9 to which the reflected light which has been focussed by said lens 3 is directed.
The mirror mounting part 6 and mirror securing part 8 are disposed in a symmetrical manner with the mirror mounting part 5 and mirror securing part 7 around the vertical central axis as shown in FIG. 3(b).
However, the prior art has problems which are described as follows:
Since the plurality of mirrors 4 are mounted within the casing 1 by means of mirror mounting parts 5 (6) and mirror securing parts 7 (8), there are provided a number of parts, resulting in an increased number of assembly steps and increased manufacturing cost.
Generally, the present invention has been achieved in view of the above mentioned problems of the prior art. It is an object of the present invention to provide an image reading apparatus which is capable of achieving reduction in cost of components and reduction in the number of assembly steps in a production line by reducing the number of components in the image reading apparatus.
Further, objects of the present invention will become apparent in light of the disclosure herein.
In order to accomplish the above-mentioned object, the image reading apparatus according to a first aspect of the present invention is characterized in that the apparatus comprises a casing which is provided with a unit to which light reflected from an original document surface having images recorded thereon is incident, a lens converging the reflected light, an image sensor to which the reflected light which has been converged by the lens is incident, and a plurality of reflectors disposed between the light incident unit and the lens for defining an optical path for the reflected light therebetween, the reflectors being formed on the inner surface of the casing in a plurality of posit ions thereof by vacuum depositing aluminum thereon.
The image reading apparatus according to a second aspect is characterized in that a bracing raised portion is formed at a part of the casing, the reflectors being formed on the inner surface of the raised portion by vacuum depositing aluminum thereon.
According to a third aspect of the present invention, the casing is made of a synthetic resin.
According to a fourth aspect of the present invention, the reflectors comprises a first reflector for reflecting the incident reflected light from the light incident unit in a direction which is substantially perpendicular to the incident direction, a second reflector for reflecting the reflected light from the first reflector in such a direction that a narrow angle is formed between the incident direction and reflecting direction, and a third reflector for reflecting the reflected light from the second reflector toward the lens.
According to a fifth aspect of the present invention, the portion of the casing is formed with the reflectors comprises a separately provided casing component.
According to a sixth aspect of the present invention, the casing component is screwed to the casing.
According to a seventh aspect of the present invention, the casing component is bonded to the casing.
According to an eighth aspect of the present invention, the image sensor comprises a CCD image sensor.
In the image reading apparatus, the mirrors may be formed directly on the inner surface of the casing by vacuum depositing aluminum thereon in position. This eliminates the necessity of special mounting parts, resulting in that reduction in the manufacturing cost can be achieved by reducing the number of parts and the number of assembly steps, and reduction in the size of the apparatus can be achieved.